Flame gun



Patented July 1, 1952 UNi'rED `srA'rl-:sn ATENT Frio 3 Claims.

This invention relates to a flame gun or flame thrower and has for one of its objects the provision of a flame gun for use in burning operations, such, for example, as are carried on by the Forestry Service, and which ame gun is adapted to operate at high efficiency over a far wider range of fuel pressure than heretofore has been possible.

The general design of ame guns of the type herein disclosed is the same in that they have a nozzle from which the fuel is ejected under the larger diameter end is open and spaced out- Wardly of said nozzle and coaxial with said axis. A wick pot is carried adjacent the open end of said element at its lower side and its open upper end opens upwardly into the element at its upper open end. This pot contains a wicking material of any suitable kind, such as asbestos and also a supply of fuel oil. The flame from the wick is to keep the fuel from the discharge nozzle ignited.

In the eld where these flame guns are used, the operator carries aportable pressure tank for the fuel, which is ordinarily diesel or stove oil, although it can be practically any of the fuel oils other than gasoline. The tank carries a manually actuatable air pump for supplying air pressure.

The ultimate desired result is to deposit as much unburned fuel oil as possible on the material to be burned. and it must be kept ignited while being so deposited. For this reason only sufficient air should be in the fuel at the time it passes the wick pot to maintain the ejected stream ignited. The ejected fuel should have a velocity of at least substantially 48.5 feet per second at the discharge nozzle.

The principal objection to previous llame guns of the present type has been that they require a tank pressure of at least 60 lbs. per square inch to provide sumcient aeration for ignition and control of the stream. This requires frequent stoppages by the operator in order to keep up the air pressure. A

One of the objects of the present invention is the provision of a nozzle design in a name gun that will produce sumcient aeration of fuel for ignition at 16 lbs. per square inch tank pressure and maintain the same control and aeration from 16 lbs. up to 100 lbs. pressure or more without adjustment of the nozzle in any Way.

This is quite important when it is realized that, for economy, the best pressure is from about 20 to 40 lbs. per square inch.

Heretofore, most efforts toward producing aeration have been directed toward producing a spiral passageway in the nozzle to swirl the ejected uid, but such expedients will not operate at a pressure below lbs. per square inch.

As already noted. the problem is not. merely one of aeration, but of only sufcient aeration to support sufficient ignition to carry a flame to the fuel that falls onto the material to be burned, and the fuel stream should not break out of control, so as to vaporize the fuel with a consequent reduction in velocity. The fuel should carry from substantially l0 to 20 feet at pressures of from about 16 to 80 lbs. per square inch with a nozzle of the size and character hereinafter described, which is a standard size for a portable flame thrower of the type illustrated.

In the drawings,

Fig. 1 is a reduced side elevational View of the flame gun with the pressure tank diagrammatically illustrated.

Fig. 2 is an enlarged part sectional and part elevational view of the gun of Fig. 1 with the central portion of the barrel broken out.

Fig. 3 is an enlarged sectional view of the nozzle which is proportionally correct, with the frusto-conical mouth element broken away at its outer end.

Fig. 4 is a diagrammatic greatly enlarged View showing the proportional relationship between the vital parts of the nozzle.

In detail, the entire assembly comprises a flame gun l having a handle 2 with a manually actuatable valve control element 3 adjacent thereto. A flexible pressure hose 4 for fuel connects the handle end of the gun and a pressure tank 5 that is equipped with a manually actuatable air pump 6 for creating the desired pressure in said tank.

The main body of the flame gun is an elongated barrel 'l having the handle 2 at one end thereof and the discharge nozzle, generally designated 8, at the opposite end.

The nozzle 8 comprises an elongated cylindrical member I0 that is formed with a bore Il therein in one end of which the outer end of barrel 'l is threaded.

The diameter of bore Il is substantially the same diameter as that of the bore in the barrel 1 except at its end that is remote from the barrel Where said diameter is reduced as at I2.

A valve rod I3 extends longitudinally through the barrel, being connected at one end with the control element 3 adjacent the handle 2, while the opposite end is tapered to a point to seat adjacent the edges of bore I2 at the inner end of the latter. Element 3 is pivoted to the handle at I4 above its connection with rod I3, and said element extends below the point of connection ybetween said val-ve rod and said element 3 to provide a trigger that is retractable by the trigger ringer of a hand grasping handle 2, the latter being in the form of a pistol grip.

A collar I'I having a plurality of apertures I8 therein is centrally secured on rod I3 and isheld against movement toward said pointed end by a keeper I9 on said rod.

The axially outwardly directed end of barrel 7 where it is within the body I0 of the nozzle, forms an axially directed shoulder 29 facing the collar I'I. A cylindrical sleeve 2I abuts the said shoulder 20, said sleeve being centrally apertured for slidably passing the rod,l3, and a plurality of passageways 23 extend through said sleeve to pass fuel into the bore II. An expansion spring 24 around rod I3 and in bore Il reacts between sleeve 2| and collar I'I to yieldably urge the pointed end of the valve', rod tightly against the edges of the restricted diameter bore I2 in member I0.

EXternally secured to member l0 at its outerv end is a frustro-conical mouth element 29, the smaller diameter end` of which is formed with a radially inwardly directed iiange that is adapted to engage anaxially outwardly directed shoulder 3l formed on the outer end of the member l0. The outsideof the outer end of member I0 is of reduced diameter and threaded, thus providing said shoulder 3 I.

Within the inner reduced diameter end of said mouth element 29 4is ahozzle cap 35 that is threaded onto the outer end of said member I0. A sealing Washer, 36 of anysuitable type may be positioned between thej cap and the flange 30 so as to provide a tight seal between the cap and the element 29.

The cap 35.has an outer end wall 38 that is centrally formed with a discharge aperture 39 coaxial with bore I2.

The wall 38 is `spacedfrom the vouter end of member Il) andas the inner diameter of said cap is substantially greater than the diameter of bore I2, the space betweensaid wall 38 and member I0 provides an enlarged chamber 49 that may be called a turbulence chamber.

The mouth element is open at its larger diameter end which is spaced a substantial distance from the discharge aperture 39, and carried by the lower side of said element adjacent its larger diameter end is a wick pot 4 2 the open upper end ofv which opens into the element 29 iiush with the inner lower side of the latter. This wick pot contains fuel oil and any suitable wicking 45, such as asbestos, so as to produce a continuous llame when ignited.

Fig. 4, the actual dimensions that are critical are given with respect to a standard sized porable flame gun as generally used with a portable pressure tank. The figures are for inches and are as follows: A=0 .O55=dia. of discharge aperture 39. v B=0.375 to 1.0=diameter of turbulence chamber 40.

C=0.03125=length of discharge aperture 39. D=0.5 to 0.625: length of turbulence chamber 40.

A lr=o.093.75:maximum die. efinlet aperture I2.,

F=0.09375=minimum length of inlet aperture I2.

Insoiar as the diameter A of the discharge aperture 39 is concerned, this can be varied 0.010" either way without materially affecting the result.

The dimension B, which is the diameter of the turbulence chamber 40, must not be less than .375" or of an inch, but it may be from .375 to 1 vinch without materially changing the result. As the diameter is reduced belowA 0.5"ithe ignition pressure increases.

The length D of the turbulence chamber, which is not less than substantially .5 or 1/ inch, permits the firing or ignition of the fuel at 16 lbs.

pressure at the orifice or aperture 39, and which rpressure will produce a velocity of 48.5 feet per second. Ii this length is reduced, the pressure at which the firing takes place is increased. For example, should the gap or length be reduced to 1/8 inch, it would require a minimum of 60 lbs. Vpressure (94.5 feetper second yelocity) to produce suicient aeration for ignition. IffA the length were increased a vdistance beyond 5/8 inch (.625f) aeration drops ofifrapidly and` increased pressure is required the sameas when'the length isreduced. rThe diameter Eof theinlet1aperture-l2,issie" or .09375fand'is proportionally-the ,maximum diameter for dimensionsA and 'D. jEvenf the slight increase of 0.010" in""diameter 'o fjlil shows decided loss. in aeration o the stream'projected through discharge vapertlzire 39. The diameter E should, of course, not be' less than' the diameter A and is preferably "substantially YThe 1e'n`gi-.h n er .the bore lz'jis `het jeritical' eircept that it should not be 'less than "09375 ore'. .Y Y,

The dimensions A, C, D "and Efare,' proportionate within relativelyynarrow limits. Thefcorrlbination is in balance hydraulically 'to' pro Vune aeration ofthe fuel streamsuficient Aforigrtion of the fuel at a pressure tas low "as 1'6'lbs."(48.5 feet per second). Y I v- Y The ultimate purpose 'of the combinationlis'to produce sufficient aeration of fuel Lforig'r'iitin at 16 lb. tank pressure'a'ndto maintain the ysame control and aeration as the pressure is 'increased to 10Q lbs. for more. A If.' the combination'is'dimensionally unbalancedv y(hydraulic unbalance) 'it would possibly work'satisfadtorily" at one sure point, b'utat no other point within't i sired range. By a slight changeindimns'ions A, C, DorfE firing and control may be obtained at 16 lbs.ftankpressure,`jbut above or"b elovww'such pressure the stream 'wculdbre'ak 'cnt .of con 'rol andthe vdevice would be 'useless j 'likexwis'ef'` a combination may be 'produced for Aproperlyliring at 'say 50 lbs. tank .pressure', but the stream'would not ignite below'thatjpress'inje, `a ltl'1oug h"litl may 'bepres'sura With thel present invenjt 1c n}fjtlief'streamTwill properly reat thelowest' possible pressure point (for diesel oi1) and ',Will" maintain'thatcontrol and stream characteristic a tj any"`poin t' 'in the defines the outlet aperture and the other end of which denes the inlet aperture, the portion of the borek between said inlet aperture and said outlet aperture being enlarged, the length of said outlet aperture axially thereof being substantially half its diameter and the diameter of said inlet aperturev being at least three times the length of said outlet aperture and the diameter of said enlarged portion being at least about seven times greater than the diameter o1' said outlet aperture with the vspacing between said outlet aperture and said` inlet aperture being at least substantially ten times greater than the diameter of said outlet, the diameter of said outlet aperture being substantially from .04" to .06.

2. In a iiame thrower including a discharge end having a generally irusto-conical mouth element and means for providing an ignition flame at its larger diameter open end, a nozzle secured to the smaller diameter end of said element having a discharge aperture coaxial with said element and directed toward said larger diameter end, said nozzle having a through bore, one end of which denes said discharge aperture and the other end of which defines the edges of an inlet aperture. the portionv of said bore between said inlet aperture and said outlet aperture being enlarged, the length of said outlet aperture axially thereof being substantially .03125" and the diameter of said outlet aperture being substantially .055, the diameter of said inlet aperture being from .055 to .09375" and not'great than the latter, the diameter of said enlarged portion being from .375" to 1" and the length of said enlarged portion axially thereof being from .5" to .625 and the length of said inlet aperture being no less than .09375".

3. In a flame thrower including a discharge end having means for producing an ignition iiame for igniting oil discharged through said discharge end, a nozzle for producing aeration of oil discharged through said discharge end at comparatively low pressure, said nozzle having a through bore one end of which defines the outlet aperture and the other end of which defines the inlet aperture, the portion of the bore between said inlet aperture and said outletaperture being enlarged, the diameter of said inlet aperture being substantially greater than the diameter of said outlet aperture but less than twice the latter and the length of said inlet aperture axially thereof being at least equal to its diameter, the length of said enlarged portion being at least equal to ve times the diameter of said inlet aperture and the length of said outlet aperture being less than its diameter, the diameter of said outlet aperture being substantially from .04" to .06".

FRED W. FUNKE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,340,012 Cane, et al May 11, 1920 1,502,104 Lieber July 22, 1924 FOREIGN PATENTS Number Country l Date 7,524 Great Britain of 1915 18,119 Great Britain of 1915 20,592 Australia of 1934 373,218 Great Britain May 17, 1932 

